U.S. patent application number 11/854075 was filed with the patent office on 2008-03-13 for alignment apparatus and alignment method.
This patent application is currently assigned to SEIKO EPSON CORPORATION. Invention is credited to Kazutoshi GOTO, Yasuo INAOKA, Takuma OKAMURO, Motonori OKUMURA, Mutsuhiko OTA, Isao YANAGISAWA.
Application Number | 20080062420 11/854075 |
Document ID | / |
Family ID | 39169271 |
Filed Date | 2008-03-13 |
United States Patent
Application |
20080062420 |
Kind Code |
A1 |
OKAMURO; Takuma ; et
al. |
March 13, 2008 |
ALIGNMENT APPARATUS AND ALIGNMENT METHOD
Abstract
An alignment apparatus, which is used when positioning and
joining a plurality of workpieces relative to each other, each
workpiece having a plurality of alignment marks for alignment, the
alignment apparatus includes: a transparent mask provided with
reference marks with which the alignment marks are aligned; a
mirror disposed between the mask and the workpiece; an optical unit
having an optical axis pointed in a direction of the mirror via the
reference mark from a side of the mask opposite to the mirror, the
optical unit enabling the reference mark and a virtual image of the
reference mark reflected in the mirror to be observed
simultaneously; and an adjusting unit for making optical axis
adjustment of the optical axis, based on the observation by the
optical unit, such that a real image of the reference mark and the
virtual image of the reference mark reflected in the mirror are
superposed.
Inventors: |
OKAMURO; Takuma;
(Nagano-ken, JP) ; OKUMURA; Motonori; (Nagano-ken,
JP) ; OTA; Mutsuhiko; (Nagano-ken, JP) ; GOTO;
Kazutoshi; (Nagano-ken, JP) ; YANAGISAWA; Isao;
(Chino-shi, JP) ; INAOKA; Yasuo; (Shiojiri-shi,
JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 Pennsylvania Avenue, N.W.
Washington
DC
20037
US
|
Assignee: |
SEIKO EPSON CORPORATION
4-1, Nishishinjuku 2-chome
Tokyo
JP
|
Family ID: |
39169271 |
Appl. No.: |
11/854075 |
Filed: |
September 12, 2007 |
Current U.S.
Class: |
356/401 |
Current CPC
Class: |
B41J 2/161 20130101;
B41J 29/393 20130101; G01B 11/272 20130101; B41J 2002/14362
20130101; B41J 2/1623 20130101 |
Class at
Publication: |
356/401 |
International
Class: |
G01B 11/00 20060101
G01B011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 13, 2006 |
JP |
2006-248740 |
Claims
1. An alignment apparatus, which is used when positioning and
joining a plurality of workpieces relative to each other, each
workpiece having a plurality of alignment marks for alignment, the
alignment apparatus comprising: a transparent mask provided with
reference marks with which the alignment marks are aligned; a
mirror disposed between the mask and the workpiece; an optical unit
having an optical axis pointed in a direction of the mirror via the
reference mark from a side of the mask opposite to the mirror, the
optical unit enabling the reference mark and a virtual image of the
reference mark reflected in the mirror to be observed
simultaneously; and an adjusting unit for making optical axis
adjustment of the optical axis, based on the observation by the
optical unit, such that a real image of the reference mark and the
virtual image of the reference mark reflected in the mirror are
superposed.
2. The alignment apparatus according to claim 1, wherein the mirror
is disposed such that when a distance from the reference mark of
the mask to the alignment mark of the workpiece is d, a distance
from the reference mark to the mirror is (1/2)d.
3. The alignment apparatus according to claim 1, wherein the mask
has a protrusion protruding along the optical axis toward the
alignment mark, and the reference marks are provided in the
protrusion.
4. The alignment apparatus according to claim 1, further
comprising: a plurality of the optical units having a plurality of
the optical axes independent of each other.
5. The alignment apparatus according to claim 1, wherein the
optical unit is composed of a bifocal microscope including two
optical systems having the optical axis in common, one of the
optical systems being capable of focusing on the real image of the
reference mark, and the other optical system being capable of
focusing on the virtual image of the reference mark reflected in
the mirror.
6. The alignment apparatus according to claim 1, wherein the
workpiece is a liquid-jet head.
7. An alignment method, which is used when positioning and joining
a plurality of workpieces relative to each other, each workpiece
having a plurality of alignment marks for alignment, the alignment
method comprising the steps of: disposing a mirror between a mask
and the workpiece such that the mask and the mirror are opposed to
each other, the mask, as a transparent member, being provided with
reference marks with which the alignment marks are aligned, the
mirror reflecting an image of the reference mark to form a virtual
image of the reference mark; simultaneously observing the reference
mark and the virtual image of the reference mark reflected in the
mirror by an optical unit having an optical axis pointed in a
direction of the mirror from a side of the mask; and making optical
axis adjustment of the optical axis, based on the observation by
the optical unit, such that a real image of the reference mark and
the virtual image of the reference mark reflected in the mirror are
superposed.
Description
[0001] The entire disclosure of Japanese Patent Application No.
2006-248740 filed Sep. 13, 2006 is expressly incorporated by
reference herein.
BACKGROUND
[0002] 1. Technical Field
[0003] This invention relates to an alignment apparatus and an
alignment method, which are useful, particularly, when used in
adjusting the optical axis of an optical means in a predetermined
manner.
[0004] 2. Related Art
[0005] An ink-jet recording apparatus, such as an ink-jet printer
or an ink-jet plotter, is equipped with an ink-jet recording head
unit (may be hereinafter referred to as a head unit) including an
ink-jet recording head which ejects, as ink droplets, ink
accommodated in a liquid accommodation portion such as an ink
cartridge or an ink tank. The ink-jet recording head has nozzle
rows comprising rows of nozzle orifices arranged in parallel, and
has its ink ejection surface side covered with a cover head. The
cover head has a window frame portion having an opening window
portion provided on the ink droplet ejection surface side of the
ink-jet recording head for exposing the nozzle orifices, and has a
side wall portion formed by being bent from the window frame
portion beside the side surface of the ink-jet recording head. The
cover head is fixed by having the side wall portion joined to the
side surface of the ink-jet recording head (see, for example,
JP-A-2002-160376 (page 4, FIG. 3)).
[0006] When the cover head and a fixing member, such as a fixing
plate, are to be joined to a plurality of the ink-jet recording
heads, the ink-jet recording heads are moved with respect to the
fixing member for predetermined positioning so that an alignment
mark provided in a nozzle plate of the ink-jet recording head
aligns with a reference mark provided in a flat plate-shaped glass
mask. In further detail, the reference mark and the alignment mark
corresponding positionally thereto are simultaneously observed with
an optical means having the optical axis pointed in the direction
of the alignment mark from the mask side via the reference mark,
and the position of the ink-jet recording head is adjusted based on
the observation such that the reference mark and the alignment mark
are superimposed. Thus, it is desirable for the optical axis of the
optical means to be pointed accurately in the direction of the
reference mark and the alignment mark.
[0007] To achieve the rapidity or rationalization of alignment, in
particular, it is conceivable to carry out alignment with two
alignment marks of one ink-jet recording head as a workpiece, at a
stroke, while observing the two alignment marks by use of optical
means such as two microscopes. In this case, it is necessary to
make adjustments so as to avoid relative displacement of the
optical axes of the respective optical means.
[0008] An earlier technology concerned with this type of optical
axis alignment was designed to carry out alignment in consideration
of the amount of displacement of the alignment mark due to
inclination between the optical axis and the alignment
mark/workpiece (see, for example, JP-A-2001-153608 (page 4, FIG.
2)).
[0009] With the above-mentioned optical axis alignment method
according to the earlier technology, however, the amount of
displacement needs to be computed, and a correction is made based
on the amount of displacement found by computation. Thus, the
alignment mark cannot be visually recognized, and alignment is
difficult.
[0010] Such problems occur not only during alignment associated
with the production of an ink-jet recording head unit, but also
during alignment associated with the production of other liquid-jet
head units.
SUMMARY
[0011] An advantage of some aspects of the present invention is to
provide an alignment apparatus and an alignment method which can
adjust the optical axis of an optical means easily into a normal
state and contribute to high accuracy alignment.
[0012] According to an aspect of the invention, there is provided
an alignment apparatus, which is used when positioning and joining
a plurality of workpieces relative to each other, each workpiece
having a plurality of alignment marks for alignment, the alignment
apparatus comprising: a transparent mask provided with reference
marks with which the alignment marks are aligned; a mirror disposed
between the mask and the workpiece; an optical unit having an
optical axis pointed in a direction of the mirror via the reference
mark from a side of the mask opposite to the mirror, the optical
unit enabling the reference mark and a virtual image of the
reference mark reflected in the mirror to be observed
simultaneously; and an adjusting unit for making optical axis
adjustment of the optical axis, based on the observation by the
optical unit, such that a real image of the reference mark and the
virtual image of the reference mark reflected in the mirror are
superposed.
[0013] According to this aspect, the optical axis is adjusted,
based on the observation by the optical unit, such that the real
image of the reference mark and the virtual image of the reference
mark reflected in the mirror are superposed. Upon completion of
such adjustment, the optical axis is perpendicular to the mask. If
alignment is performed such that the reference mark and the
alignment mark are located on this optical axis, therefore, high
accuracy positioning of the workpiece can be accomplished.
[0014] It is preferable that the mirror is disposed such that when
a distance from the reference mark of the mask to the alignment
mark of the workpiece is d, a distance from the reference mark to
the mirror is (1/2)d.
[0015] According to this embodiment, the position of the virtual
image of the reference mark reflected in the mirror can be brought
into coincidence with the position of the alignment mark of the
workpiece. Thus, if the focal position of the optical unit is
brought to the virtual image, the alignment mark can be
automatically focused on during alignment. Consequently, high
accuracy positioning can be easily carried out, including
focusing.
[0016] It is also preferable that the mask has a protrusion
protruding along the optical axis toward the alignment mark, and
the reference marks are provided in the protrusion.
[0017] According to this embodiment, the distance between the
reference mark and the alignment mark can be reduced. As a result,
displacement of the optical axis can be minimized. Moreover, the
mask can be supported by a thick member, namely, a member having
sufficient rigidity, and displacement due to warpage of the member
or the like is not caused. Thus, even higher accuracy positioning
can be carried out.
[0018] It is also preferable that the alignment apparatus further
comprises a plurality of the optical units having a plurality of
the optical axes independent of each other.
[0019] According to this embodiment, the optical axis of the
optical unit can be adjusted easily. Such an embodiment can be
applied to the relative adjustment of the optical axes of a
plurality of the optical units. This is because the optical axes
after adjustment are all perpendicular to the plane of the
mask.
[0020] As a result, one workpiece can be positioned at a
predetermined position based on two of the alignment marks with the
use of the plurality of optical units. In addition, this
positioning can be performed highly accurately. That is, prompt and
highly accurate alignment can be performed for one workpiece by a
single operation.
[0021] It is also preferable that the optical unit is composed of a
bifocal microscope including two optical systems having the optical
axis in common, one of the optical systems being capable of
focusing on the real image of the reference mark, and the other
optical system being capable of focusing on the virtual image of
the reference mark reflected in the mirror.
[0022] According to this embodiment, the real image of the
reference mark and its virtual image reflected in the mirror can be
seen at the same time using the bifocal microscope. Furthermore,
the real image and the virtual image individually focused by one
optical system and the other optical system can be superimposed,
whereby predetermined optical axis adjustment can be made. That is,
the depth of field of each optical system can be minimized, and the
magnification can be increased accordingly.
[0023] As a result, the optical axis adjustment of the optical unit
can be made with high accuracy, and predetermined positioning of
the workpiece can be made with even higher accuracy.
[0024] It is also preferable that the workpiece is a liquid-jet
head.
[0025] According to this embodiment, the same actions and effects
as those in the above embodiments are obtained for alignment of the
plurality of liquid-jet heads.
[0026] According to another aspect of the invention, there is
provided an alignment method, which is used when positioning and
joining a plurality of workpieces relative to each other, each
workpiece having a plurality of alignment marks for alignment, the
alignment method comprising the steps of: disposing a mirror
between a mask and the workpiece such that the mask and the mirror
are opposed to each other, the mask, as a transparent member, being
provided with reference marks with which the alignment marks are
aligned, the mirror reflecting an image of the reference mark to
form a virtual image of the reference mark; simultaneously
observing the reference mark and the virtual image of the reference
mark reflected in the mirror by an optical unit having an optical
axis pointed in a direction of the mirror from a side of the mask;
and making optical axis adjustment of the optical axis, based on
the observation by the optical unit, such that a real image of the
reference mark and the virtual image of the reference mark
reflected in the mirror are superposed.
[0027] According to this embodiment, the optical axis is adjusted,
based on the observation by the optical unit, such that the real
image of the reference mark and the virtual image of the reference
mark reflected in the mirror are superposed. Upon completion of
such adjustment, the optical axis can be rendered perpendicular to
the mask. If alignment is performed such that the reference mark
and the alignment mark are located on this optical axis, therefore,
high accuracy positioning of the workpiece can be accomplished.
Even in the presence of a plurality of the optical axes, relative
relationship between the optical axes can be rendered constant with
ease.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The invention will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements.
[0029] FIG. 1 is an exploded perspective view of a head unit for
which predetermined alignment is performed according to an
embodiment of the invention.
[0030] FIG. 2 is a perspective view of the head unit after
assembly.
[0031] FIG. 3 is a sectional view of essential portions of the head
unit.
[0032] FIG. 4 is an exploded perspective view of the essential
portions of the head unit.
[0033] FIG. 5 is a sectional view showing a recording head and a
head case of the head unit.
[0034] FIG. 6 is a sectional view showing an alignment apparatus
according to the embodiment of the invention.
[0035] FIG. 7 is a sectional view taken on line A-A in FIG. 6.
[0036] FIGS. 8A to 8C are explanation drawings showing, in an
enlarged manner, parts of FIG. 6.
[0037] FIGS. 9A to 9C are bottom views for illustrating a
positioning method using the alignment apparatus.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0038] Ink-Jet Recording Head Unit:
[0039] Prior to describing an alignment apparatus according to an
embodiment of the invention, an explanation will be offered for an
ink-jet recording head unit having an ink-jet recording head. The
ink-jet recording head is an example of a workpiece which undergoes
the alignment concerned.
[0040] FIG. 1 is an exploded perspective view of the ink-jet
recording head unit. FIG. 2 is a perspective view of the ink-jet
recording head unit after assembly. FIG. 3 is a sectional view of
essential portions of the ink-jet recording head unit.
[0041] As shown in these drawings, an ink-jet recording head unit
200 (to be referred to hereinafter as head unit 200) has a
cartridge case 210, an ink-jet recording head 220, a cover head
240, and a fixing plate 250.
[0042] Of these members, the cartridge case 210 is a holding member
for ink cartridges (not shown), which has a cartridge mounting
portion 211 where the ink cartridges are mounted. The ink
cartridges are ink supply means which are individually composed
and, for example, filled with a black ink and three-color inks.
That is, the cartridge case 210 is mounted with the ink cartridges
of different colors.
[0043] As specified, particularly, in FIG. 3, the cartridge case
210 is provided with a plurality of ink communicating paths 212
each of which has one end opening to the cartridge mounting portion
211, and the other end opening to a head case 230. To portions of
the cartridge mounting portion 211 where the ink communicating
paths 212 are open, ink supply needles 213 are fixed which are
inserted into ink supply ports of the ink cartridges. This fixing
is carried out via filters (not shown) which are formed in the ink
communicating paths 212 in order to remove air bubbles or foreign
matter within ink.
[0044] The head case 230 is secured to the bottom surface of the
cartridge case 210. The ink-jet recording head 220 has a plurality
of piezoelectric elements 300, and ejects ink droplets through a
nozzle orifice 21 at an end surface on a side opposite to the
cartridge case 210 by driving of the piezoelectric element 300. A
plurality of the ink-jet recording heads 220 are provided in
correspondence with the different ink colors so as to eject the
different colors of inks from the ink cartridges. Thus, a plurality
of the head cases 230 are provided independently in correspondence
with the ink-jet recording heads 220.
[0045] The above-described ink-jet recording head 220 and head case
230 will be described in further detail by additional reference to
FIGS. 4 and 5. FIG. 4 is an exploded perspective view of the
essential portions of the ink-jet recording head 220 and the head
case 230. FIG. 5 is a sectional view of the ink-jet recording head
220 and the head case 230.
[0046] As shown in FIGS. 4 and 5, the ink-jet recording head 220 is
composed of four plates, i.e., a nozzle plate 20, a passage-forming
substrate 10, a protective plate 30, and a compliance plate 40. Of
these plates, the passage-forming substrate 10, in the present
embodiment, comprises a single crystal silicon substrate, and has
an elastic film 50 formed on one surface thereof, the elastic film
50 comprising silicon dioxide formed by thermal oxidation. In the
passage-forming substrate 10, pressure generating chambers 12
separated by a plurality of compartment walls are formed. In the
present embodiment, the pressure generating chambers 12 are
arranged in sets of two in the width direction of the
passage-forming substrate 10, forming two rows of the pressure
generating chambers 12. These pressure generating chambers 12 have
been created by anisotropic etching performed from the other
surface of the passage-forming substrate 10. Longitudinally
outwardly of the pressure generating chambers 12 of each row, a
communicating portion 13 is formed which communicates with a
reservoir portion 31 provided in the protective plate 30 (to be
described later) to constitute a reservoir 100 serving as a common
ink chamber for the pressure generating chambers 12. The
communicating portion 13 is in communication with an end portion in
the longitudinal direction of each pressure generating chamber 12
via an ink supply path 14.
[0047] The nozzle plate 20 is secured to the opening surface side
of the passage-forming substrate 10 via an adhesive agent, a
heat-fused film or the like. The nozzle plate 20 has the nozzle
orifices 21 each of which communicates with each pressure
generating chamber 12 on a side opposite to the ink supply path 14.
In the present embodiment, one ink-jet recording head 220 is
provided with two nozzle rows 21A comprising two rows of the nozzle
orifices 21 arranged parallel.
[0048] The nozzle plate 20 can be formed preferably from a
glass-ceramics, a single crystal silicon substrate, or a stainless
steel which has a thickness, for example, of 0.01 to 1 mm, and a
coefficient of linear expansion, for example, of 2.5 to 4.5
(10.sup.-6/.degree. C.) at 300.degree. C. or lower. The nozzle
plate 20 is provided with an alignment mark 22 (to be described in
detail later) which is used for alignment with the fixing plate
250. In the present embodiment, two of the alignment marks 22 are
provided at end portions in the parallel-arrangement direction of
the nozzle orifices 21.
[0049] On the side of the passage-forming substrate 10 opposite
from its opening surface, the piezoelectric elements 300 are
disposed on the elastic film 50. The piezoelectric elements 300 are
formed by sequentially stacking an insulation film 55 comprising
zirconium oxide, a lower electrode film comprising a metal, a
piezoelectric layer comprising lead zirconate titanate (PZT) or the
like, and an upper electrode film comprising a metal.
[0050] The protective plate 30 is joined onto the passage-forming
substrate 10 on which the piezoelectric elements 300 are formed.
The reservoir portion 31, in the present embodiment, is formed to
penetrate the protective plate 30 in its thickness direction and to
extend in the width direction of the pressure generating chamber
12. As stated earlier, the reservoir portion 31 is brought into
communication with the communicating portion 13 of the
passage-forming substrate 10 to constitute the reservoir 100
serving as the common ink chamber for the pressure generating
chambers 12. In a region of the protective plate 30 opposite the
piezoelectric element 300, a piezoelectric element holding portion
32 is provided which has a space enough not to impede the movement
of the piezoelectric element 300. Such a protective plate 30 can be
suitably formed from glass, ceramic, metal, or plastic, but it is
preferred to use a material having nearly the same thermal
expansion coefficient as that of the passage-forming substrate 10.
In the present embodiment, the protective plate 30 is formed using
a single crystal silicon substrate which is the same material as
that of the passage-forming substrate 10.
[0051] A drive IC 110 for driving each piezoelectric element 300 is
provided on the protective plate 30. Each terminal of the drive IC
110 is connected to lead-out wiring withdrawn from an individual
electrode of each piezoelectric element 300 via a bonding wire or
the like (not shown). Each terminal of the drive IC 110 is
connected to the outside via external wiring 111, such as a
flexible printed cable (FPC), as shown in FIG. 1 to receive various
signals, such as a print signal, from the outside via the external
wiring 111.
[0052] The compliance plate 40 is joined onto the protective plate
30. In a region of the compliance plate 40 opposed to the reservoir
100, an ink introducing port 44 for supplying ink to the reservoir
100 is formed to penetrate the compliance plate 40 in its thickness
direction. A region, other than the ink introducing port 44, in the
region of the compliance plate 40 opposed to the reservoir 100
defines a flexible portion 43 formed thinly in the thickness
direction. The reservoir 100 is sealed with the flexible portion
43. The flexible portion 43 imparts compliance to the interior of
the reservoir 100. In more detail, the head case 230 having ink
supply communicating paths 231 is provided on the compliance plate
40. In the head case 230, a depression 232 is formed in a region
opposed to the flexible portion 43 so that flexible deformation of
the flexible portion 43 takes place, as appropriate.
[0053] In the head case 230, a drive IC holding portion 233
penetrating the head case 230 in the thickness direction is
provided in a region opposed to the drive IC 110 provided on the
protective plate 30. The external wiring 111 is inserted through
the drive IC holding portion 233, and connected to the drive IC
110.
[0054] With the ink-jet recording head 220 of the above-described
configuration, ink from the ink cartridge is taken in through the
ink introducing port 44 via the ink communicating path 212 (see
FIG. 3) and the ink supply communicating path 231, filling up the
interior of the head ranging from the reservoir 100 to the nozzle
orifices 21. In this state, according to recording signals from the
drive IC 110, voltage is applied to the respective piezoelectric
element 300 corresponding to the pressure generating chamber 12 to
flexibly deform the elastic film 50 and the piezoelectric element
300. As a result, the pressure inside the pressure generating
chamber 12 rises to eject ink droplets through the nozzle orifice
21.
[0055] The respective members constituting the ink-jet recording
head 220, and the head case 230 are provided with pin insertion
holes 234, at two locations of corner portions thereof, for
insertion of pins for positioning the respective members during
assembly. By inserting the pins into the pin insertion holes 234 to
position the respective members relatively, while joining the
members to each other, the ink-jet recording head 220 and the head
case 230 are combined integrally.
[0056] The above-mentioned ink-jet recording head 220 is formed by
forming many chips simultaneously on a single silicon wafer,
adhering them to the nozzle plate 20 and the compliance plate 40 to
integrate these members, and then dividing the composite for each
passage-forming substrate 10 of one chip size as shown in FIG.
4.
[0057] Four of the ink-jet recording heads 220 and four of the head
cases 230 are fixed to the cartridge case 210 with predetermined
spacing in the direction of parallel arrangement of the nozzle rows
21A, as shown in FIGS. 1 to 3. That is, the head unit 200 is
provided with eight of the nozzle rows 21A.
[0058] As described above, there are provided many of the nozzle
rows 21A comprising rows of the nozzle orifices 21 arranged
parallel using the plurality of the ink-jet recording heads 220. By
so doing, a decrease in yield can be prevented in comparison with
the formation of many of the nozzle rows 21A in the single ink-jet
recording head 220. Furthermore, the plurality of ink-jet recording
heads 220 are used to achieve the arrangement of the multiple
nozzle rows 21A. By so doing, it becomes possible to increase the
yield of the ink-jet recording heads 220 which can be formed from
the single silicon wafer. This can narrow the wasteful region of
the silicon wafer to cut down on the cost of production.
[0059] The above four ink-jet recording heads 220 are positioned
and held by the fixing plate 250, which is the common fixing member
joined to the ink droplet ejection surfaces of the plural ink-jet
recording heads 220, as shown in FIGS. 1 and 3. The fixing plate
250 comprises a flat plate, and has an exposure opening portion 251
which exposes the nozzle orifices 21, and a joining portion 252
which demarcates the exposure opening portion 251 and which is
joined at least to opposite end portions, beside the nozzle rows
21A, of the ink droplet ejection surface of the ink-jet recording
head 220.
[0060] The joining portion 252 is composed of a fixing frame
portion 253 provided along the outer periphery of the ink droplet
ejection surfaces of the plural ink-jet recording heads 220, and a
fixing beam portion 254 extending between the adjacent ink-jet
recording heads 220 to divide the exposure opening portion 251. The
joining portion 252 comprising the fixing frame portion 253 and the
fixing beam portion 254 is joined altogether to the ink droplet
ejection surfaces of the plural ink-jet recording heads 220. The
fixing frame portion 253 of the joining portion 252 is formed to
close the pin insertion holes 234 which position the respective
members during manufacture of the ink-jet recording head 220.
[0061] The preferred material for the fixing plate 250 is, for
example, a metal such as stainless steel, glass-ceramics, or a
single crystal silicon plate. For the fixing plate 250, it is
preferred to use a material having the same thermal expansion
coefficient as that of the nozzle plate 20 in order to prevent
deformation due to the difference in thermal expansion from the
nozzle plate 20. For example, when the nozzle plate 20 is formed
from a single crystal silicon plate, it is preferred to form the
fixing plate 250 from a single crystal silicon plate.
[0062] The fixing plate 250 is preferably formed thinly, desirably
more thinly than the cover head 240 to be described later. If the
fixing plate 250 is thick, ink is apt to remain, for example,
between the ink droplet ejection surface of the nozzle plate 20 and
the fixing beam portion 254 when the ink droplet ejection surface
is wiped. However, the fixing plate 250 is formed thinly, whereby
ink can be prevented from remaining on the ink droplet ejection
surface of the nozzle plate 20 during wiping.
[0063] In the present embodiment, the thickness of the fixing plate
250 is set at 0.1 mm. The manner of joining between the fixing
plate 250 and the nozzle plate 20 is not limited, and can be
performed suitably, for example, using a thermosetting epoxy-based
adhesive agent, or an ultraviolet curing adhesive agent.
[0064] As noted above, the fixing plate 250 closes the spaces
between the adjacent ink-jet recording heads 220 by its fixing beam
portion 254. Thus, ink does not enter the spaces between the
adjacent ink-jet recording heads 220, and this can prevent
ink-associated deterioration and destruction of the members of the
ink-jet recording head 220, such as the piezoelectric element 300
and the drive IC 110. Moreover, the ink droplet ejection surface of
the ink-jet recording head 220 and the fixing plate 250 are adhered
together, without clearance, by the adhesive agent. Thus, the entry
of a recording medium into the clearance, if any, can be prevented
to prevent deformation of the fixing plate 250 and a paper jam.
[0065] As seen above, the above head unit 200 has the four ink-jet
recording heads 220 secured to the fixing plate 250. Positioning of
the ink-jet recording head 220 onto the fixing plate 250 is
performed using an alignment apparatus to be described later.
[0066] Further, the head unit 200 is provided with the cover head
240, which is box-shaped to cover the respective ink-jet recording
heads 220, on a side of the fixing plate 250 opposite from the
ink-jet recording head 220, as shown in FIGS. 1 and 2. The cover
head 240 has a fixing portion 242 provided with an opening portion
241 in correspondence with the exposure opening portion 251 of the
fixing plate 250, and a side wall portion 245 provided on the
lateral side of the ink droplet ejection surfaces of the ink-jet
recording heads 220 so as to bend around the outer periphery of the
fixing plate 250.
[0067] The fixing portion 242 is composed of a frame portion 243
provided in correspondence with the fixing frame portion 253 of the
fixing plate 250, and a beam portion 244 provided in correspondence
with the fixing beam portion 254 of the fixing plate 250 to divide
the opening portion 241. The fixing portion 242 comprising the
frame portion 243 and the beam portion 244 is joined to the joining
portion 252 of the fixing plate 250.
[0068] As noted above, the ink droplet ejection surface of the
ink-jet recording head 220 and the cover head 240 are joined
together without clearance. Thus, the entry of a recording medium
into the clearance, if any, can be prevented to prevent deformation
of the cover plate 240 and a paper jam. Moreover, the side wall
portion 245 of the cover head 240 covers the outer peripheral edge
portion of the plural ink-jet recording heads 220, thus reliably
preventing the wraparound of ink onto the side surface of the
ink-jet recording head 220.
[0069] Examples of the material for the cover head 240 are metallic
materials such as stainless steel. The cover head 240 may be formed
by press working or molding a plate of such a metal. Also, the
cover head 240 can be grounded if it is formed of an
electroconductive metallic material.
[0070] Furthermore, the cover head 240 needs a certain degree of
strength in order to protect the ink-jet recording head 220 from
impact by wiping or capping. Thus, the cover head 240 needs to be
relatively thick. In the present embodiment, the thickness of the
cover head 240 is set at 0.2 mm.
[0071] The method of joining between the cover head 240 and the
fixing plate 250 is not limited, and is, for example, adhesion
using a thermosetting epoxy-based adhesive agent.
[0072] The fixing portion 242 is provided with flange portions 246
having fixing holes 247 for positioning and fixing the cover head
240 onto other member. The flange portion 246 is provided to bend
so as to protrude from the side wall portion 245 in the same
direction as the plane direction of the ink droplet ejection
surface. The cover head 240 in the present embodiment is fixed to
the cartridge case 210, which is the holding member holding the
ink-jet recording heads 220 and the head cases 230, as shown in
FIGS. 2 and 3.
[0073] In further detail, as shown in FIGS. 2 and 3, the cartridge
case 210 is provided with protrusions 215 which protrude on the ink
droplet ejection surface side and which are inserted into the
fixing holes 247 of the cover head 240. By inserting the
protrusions 215 into the fixing holes 247 of the cover head 240 and
heating and caulking leading end portions of the protrusions 215,
the cover head 240 is fixed to the cartridge case 210. The
protrusion 215 provided on the cartridge case 210 is allowed to
have a smaller outer diameter than that of the fixing hole 247 of
the flange portion 246, whereby the cover head 240 can be
positioned in the plane direction of the ink droplet ejection
surface and fixed to the cartridge case 210.
[0074] The cover head 240 and the fixing plate 250 having the
plurality of ink-jet recording heads 220 joined thereto are fixed
together, with the fixing holes 247 of the cover head 240 and the
plurality of nozzle rows 21A being positioned with respect to each
other. This positioning between the fixing holes 247 of the cover
head 240 and the plurality of nozzle rows 21A can be performed
using the alignment apparatus to be described later. Alternatively,
when the fixing plate 250 and the plurality of ink-jet recording
heads 220 are positioned and fixed, the cover head 240 may
simultaneously be positioned and fixed.
Embodiment
[0075] The alignment apparatus according to an embodiment of the
invention will be described in detail with reference to the
accompanying drawings. The same portions as those in FIGS. 1 to 5
are assigned the same numerals as those therein.
[0076] FIG. 6 is a sectional view showing the alignment apparatus
according to the embodiment of the invention. FIG. 7 is a sectional
view taken on line A-A in FIG. 6. As shown in this drawing, the
alignment apparatus according to this embodiment has two optical
means composed of bifocal microscopes 500 and 600. This alignment
apparatus is designed to be capable of positioning one ink-jet
recording head at a predetermined position by use of two alignment
marks.
[0077] As shown in FIGS. 6 and 7, the alignment apparatus according
to the present embodiment has an alignment jig 400 on which the
ink-jet recording heads 220 are placed, a pressing means 450 for
pressing the ink-jet recording heads 220 against the fixing plate
250 integrally with the alignment jig 400, and the two bifocal
microscopes 500 and 600 each having an optical system 501, 502
(601, 602) for observing the ink-jet recording head 220 from below
the alignment jig 400 via the alignment jig 400.
[0078] Of these members, the alignment jig 400 has a mask 410
provided with reference marks 401, a base jig 420 for setting the
mask 410 in place, and a spacer jig 430 disposed on the base jig
420 for holding the fixing plate 250 as the fixing member. In this
configuration, the fixing plate 250 is held on the spacer jig 430,
and the relative positional relationship between the reference mark
401 of the mask 410 and the alignment mark 22 of the nozzle plate
20 is confirmed by the bifocal microscope 500. During this process,
alignment between the reference mark 401 and the alignment mark 22
is performed, while the fixing plate 250 and the nozzle plate 20 of
the ink-jet recording head 220 are adhered together via the
adhesive agent.
[0079] In further detail, the base jig 420 comprises stainless
steel or the like in the shape of a box opening at the bottom
surface. In the base jig 420, a single through-hole 421 penetrating
in the thickness direction is provided in a region opposed to the
region of the mask 410 where the reference mark 401 is provided.
The through-hole 421 corresponds positionally to a communicating
hole 432 of the spacer jig 430 to be described later.
[0080] The mask 410 comprises a transparent material allowing
passage of light, for example, glass such as quartz and, in the
present embodiment, has protrusions 411 which protrude into the
through-hole 421 of the spacer jig 420 and which have the reference
marks 401 formed at leading end portions thereof. The protrusion
411 is a cylindrical portion provided for each reference mark 401.
In the present embodiment, two of the alignment marks 22 are
provided in the nozzle plate 20 of each ink-jet recording head 220.
Thus, two of the reference marks 401 are provided for each ink-jet
recording head 220, so that total eight of the reference marks 401
are provided.
[0081] The reference mark 401 is preferably formed to be at a
height in the vicinity of the alignment mark 22 of the nozzle plate
20. This is intended for decreasing the distance between the
alignment mark 22 and the reference mark 401 to increase
positioning accuracy. That is, the greater the distance between the
reference mark 401 and the alignment mark 22, the more difficult it
becomes to ensure the positioning accuracy. If a great distance
exists between the reference mark 401 and the alignment mark 22,
the optical axis of the optical system 501, 502 (601, 602) is
greatly displaced because of heat of a metal halide lamp or the
like, which is used when the position is confirmed by the optical
system 501, 502 (601, 602). As a result, a great error occurs in
the actual positions of the reference mark 401 and the alignment
mark 22.
[0082] Assume that the protrusion 411 is not provided in the mask,
and the distance between the alignment mark 22 and the reference
mark 401 is, for example, about 5.1 mm. In this case, displacement
of the optical axis reaches about 2.5 .mu.m, at most. In the
present embodiment, the provision of the protrusion 411 in the mask
410 decreases the distance between the reference mark 401 and the
alignment mark 22 to 110 .mu.m or less. By so doing, the above
heat-associated displacement of the optical axis of the optical
system 501, 502 (601, 602) can be decreased to 0.05 .mu.m or less,
thus ensuring high accuracy positioning.
[0083] If the protrusion 411 comes too close to the nozzle plate
20, the adhesive agent adhering the nozzle plate 20 and the fixing
plate 250 may adhere to the leading end surface of the protrusion
411, making it impossible for the optical system 501, 502 (601,
602) to confirm the alignment mark 22 and the reference mark 401.
Thus, the leading end surface of the protrusion 411 is preferably
provided to be separated by a predetermined distance from the
nozzle plate 20.
[0084] As noted above, the distance between the alignment mark 22
and the reference mark 401 is shortened by providing the mask 410
with the protrusion 411. Thus, it becomes unnecessary to shorten
the distance between the reference mark 401 and the alignment mark
22 by reducing the thickness of the base jig 420. If the thickness
of the base jig 420 is reduced in order to shorten the distance
between the alignment mark 22 and the reference mark 401, the
following problem occurs: When the ink-jet recording head 220 is
pressed against the fixing plate 250, the base jig 420 is deformed
or destroyed. As a result, an error occurs in the alignment between
the reference mark 401 and the alignment mark 22. In the present
embodiment, on the other hand, the mask 410 is provided with the
protrusion 411. Thus, there is no need to form the base jig 420
thinly. Consequently, the rigidity of the base jig 420 can be
maintained to prevent deformation or destruction. This can also
contribute to highly accurate positioning.
[0085] The mask 410 is detachably held by the base jig 420, and can
be used in other alignment jig, for example, when the fixing plate
250 and the ink-jet recording head 220 are adhered by curing of the
adhesive agent. This can cut down on the cost of the alignment jig
400.
[0086] The spacer jig 430 is held on a surface of the base jig 420
opposite to its surface, on which the mask 410 is disposed, to hold
the fixing plate 250. In further detail, the spacer jig 430 is
provided with a plurality of suction chambers 431, each of which
comprises a plate-shaped member such as stainless steel and has a
suction means, such as a vacuum pump (not shown), connected to its
interior. The suction chamber 431 opens to the surface of the
spacer jig 430 for sucking and holding the surface of the fixing
plate 250. The spacer jig 430 is provided with communicating holes
432, each of which becomes a space, so that the alignment mark 22
of the ink-jet recording head 220 held by the fixing plate 250 upon
suction can be confirmed from below the bottom surface of the mask
410 through the communicating hole 432. That is, the spacer jig 430
is disposed between the fixing plate 250 and the mask 410 in such a
manner as to make contact, on one surface, with the fixing plate
250 and make contact, on the other surface, with the mask 410 so
that the reference mark 401 and the alignment mark 22 are opposed
to each other via the space.
[0087] The pressing means 450 for pressing the ink-jet recording
head 220 toward the fixing plate 250 is disposed on the
above-mentioned alignment jig 400. That is, the pressing means 450
has a U-shaped arm portion 451 having both ends placed on the
spacer jig 430 and arranged above the ink-jet recording head 220,
and pressing portions 453 provided in the arm portion 451 for
pressing the ink-jet recording heads 220 toward the fixing plate
250.
[0088] The pressing portions 453 are provided in regions of the arm
portion 451 opposed the respective ink-jet recording heads 220. In
the present embodiment, four of the ink-jet recording heads 220 are
fixed to the single fixing plate 250. Thus, four (the same number
as the number of the ink-jet recording heads 220) of the pressing
portions 453 are provided in correspondence with the ink-jet
recording heads 220.
[0089] Each pressing portion 453 is composed of a pressing pin 454
of a cylindrical shape inserted through the arm portion 451 and
provided to be movable in the axial direction, an urging means 455
provided on a proximal end side of the pressing pin 454 for urging
the pressing pin 454 toward the ink-jet recording head 220, and a
pressing dowel 459 placed between the pressing pin 454 and the
ink-jet recording head 220.
[0090] The pressing pin 454 has a leading end formed in a
semispherical shape, and makes a point contact with the top of the
pressing dowel 459 to press the pressing dowel 459.
[0091] The urging means 455 is provided in the arm portion 451 for
urging the pressing pin 454 toward the ink-jet recording head 220.
In the present embodiment, the urging means 455 has a thread
holding portion 456 provided to surround the proximal end side of
the pressing pin 454, a threaded portion 457 screwed to the thread
holding portion 456, and an urging spring 458 provided between the
leading end surface of the threaded portion 457 and a proximal end
portion of the pressing pin 454.
[0092] Thus, the urging means 455 can adjust the pressure, with
which the urging spring 458 presses the pressing pin 454, depending
on the amount of clamping against the thread holding portion 456 by
the threaded portion 457. By this means, the pressure with which
the pressing pin 454 presses the pressing dowel 459 can be
adjusted.
[0093] The pressing dowel 459 is placed between the pressing pin
454 and the protective plate 30 of the ink-jet recording head 220.
The pressing pin 454 makes a point contact with the upper surface
of the pressing dowel 459, and the pressing force of the pressing
pin 454 is spread uniformly to nearly the entire surface of the
protective plate 30 of the ink-jet recording head 220. In this
state, the ink-jet recording head 220 can be pressed. Instead of
bringing the leading end of the pressing pin 454 into direct
contact with the top of the protective plate 30 of the ink-jet
recording head 220, the whole of the ink-jet recording head 220 is
pressed by the pressing dowel 459. Thus, the ink-jet recording head
220 can be reliably fixed to the fixing plate 250. The pressing
dowel 459 has an outer peripheral shape of the same size as, or a
slightly smaller size than, the size of the outer peripheral shape
of the protective plate 30 of the ink-jet recording head 220.
[0094] As described above, the alignment jig 400 integrated with
the pressing means 450 is disposed on a moving table 550, and is
designed to be moved, as appropriate, in a horizontal direction
perpendicular to the optical axes L1 and L2 of the bifocal
microscopes 500 and 600. Thus, the moving table 550 is moved, with
the optical axes L1 and L2 being fixed. By so doing, each alignment
mark 22 corresponding to each ink-jet recording head 220 can be
allowed to lie on the optical axes L1, L2 together with each
reference mark 401. In a region of the moving table 550 where the
optical axes L1, L2 pass while heading for the mask 410,
through-holes 551 are provided to ensure optical paths leading to
the alignment marks 22 via the reference marks 401.
[0095] The bifocal microscope 500 has one optical system 501 and
another optical system 502 having the optical axis L1 in common.
The optical axis L1 is pointed in the direction of the alignment
mark 22 via the reference mark 401 and the communicating hole 432,
as a space, from the side of the mask 410 opposite to the spacer
jig. The optical system 501 can focus on the reference mark 401,
while the optical system 502 can focus on the alignment mark
22.
[0096] In more detail, an objective lens 503 is accommodated in a
lens-barrel 504, with the optical axis L1 being pointed in the
direction of the reference mark 401 and the alignment mark 22. The
lens-barrel 504 is fixed to a casing 505. Within the casing 505,
two beam splitters 506 and 507, two mirrors 508 and 509, and two
focal lenses 510 and 511 are accommodated.
[0097] The optical system 501 is formed from the beam splitter 506,
the mirror 508, the focal lens 510, and the beam splitter 507. The
optical system 501 has an optical path (indicated by dashed dotted
lines in the drawing) in which light, which has passed through the
beam splitter 506, is reflected by the mirror 508, passed through
the focal lens 510, and then led to the outside via the beam
splitter 507.
[0098] The optical system 502 is formed from the beam splitter 506,
the focal lens 511, the mirror 509, and the beam splitter 507. The
optical system 502 has an optical path (indicated by dashed dotted
lines in the drawing) in which light, which has been reflected by
the beam splitter 506, is passed through the focal lens 511, then
reflected by the mirror 509 and the beam splitter 507, and then led
to the outside.
[0099] A CCD 520, which is an imaging means, takes in an image of
the reference mark 401 and an image of the alignment mark 22
simultaneously via the optical systems 501 and 502, and reproduces
the images. By adjusting the focal position of the focal lens 510,
the image of the reference mark 401 is focused onto the CCD 520. By
adjusting the focal position of the focal lens 511, the image of
the alignment mark 22 is focused onto the CCD 520. In this manner,
clear images of the reference mark 401 and the alignment mark 22
can be focused individually on the CCD 520. The position of the
ink-jet recording head 220 is adjusted such that these images are
superimposed, whereby predetermined alignment is carried out.
[0100] The foregoing descriptions concern the bifocal microscope
500, and the other bifocal microscope 600 also has exactly the same
configuration. Thus, the portions of the bifocal microscope 600,
which correspond to the respective portions of the bifocal
microscope 500, are assigned numerals obtained by adding "100" to
the numerals of the respective portions of the bifocal microscope
500, in order to omit duplicate explanations.
[0101] The present embodiment has the two bifocal microscopes 500
and 600 so that the two alignment marks 22 and 22 formed at
opposite end portions in the longitudinal direction of the nozzle
plate 20 of the ink-jet recording head 220 can be observed at the
same time, and the distance between the optical axes L1 and L2 of
the bifocal microscopes 500 and 600 is in agreement with the
distance between the two alignment marks 22 and 22. Hence, when the
reference marks 401, 401 and the alignment marks 22, 22 are located
on the optical axes L1, L2, the ink-jet recording head 220 is
positioned in a predetermined manner relative to the fixing plate
250.
[0102] The procedure for the positioning is common to the two
bifocal microscopes 500 and 600. The procedure simply comprises
taking in the images of the two alignment marks 22 and 22 and the
corresponding reference marks 401 and 401 by the two bifocal
microscopes 500 and 600, and parallel-processing these images. This
procedure itself is essentially the same as that for one bifocal
microscope.
[0103] However, when parallel processing is performed using the two
bifocal microscopes 500 and 600 as above, predetermined alignment
for one ink-jet recording head 220 is completed by single
positional adjustment based on the two sets of the reference marks
401 and the alignment marks 22. Thus, a prompt alignment operation
can be performed, in comparison with an alignment operation based
on one set of the reference mark 401 and the alignment mark 22. In
the case of one bifocal microscope, in particular, predetermined
alignment is carried out for one ink-jet recording head 220 with
the use of the reference mark 401 and the alignment mark 22 located
on one side, and then predetermined alignment is carried out with
the use of the reference mark 401 and the alignment mark 22 located
on the other side. During this process, the adjusted position may
be displaced. In view of this possibility, the operating efficiency
of the above-mentioned alignment operation using the two bifocal
microscopes 500, 600 is even better.
[0104] In performing alignment using the two bifocal microscopes
500 and 600 as in the present embodiment, the optical axes L1 and
L2 of the bifocal microscopes 500 and 600 need to coincide
relatively with each other. With the alignment apparatus according
to the present embodiment, therefore, the optical axes L1 and L2
are adjusted prior to the predetermined alignment of the ink-jet
recording head 220. Thus, the alignment apparatus according to the
present embodiment has a mirror 700 for optical axis
adjustment.
[0105] A detailed description will be offered of optical axis
adjustment with the addition of FIGS. 8A to 8C. FIG. 8A is a
sectional view showing, in an extracted and enlarged manner, parts
of FIG. 6 and FIG. 7 (portions in the vicinity of the mirror 700)
during optical axis adjustment. FIG. 8B is a plan view of the
portion of the reference mark 401 viewed from above the mask 410.
FIG. 8C is an explanation drawing conceptually showing a real image
of the reference mark 401 and a virtual image of the reference mark
401 reflected in the mirror 700 which are obtained as image
information by the bifocal microscope 500, 600.
[0106] As shown in FIG. 8A, the reference mark 401 with which the
alignment mark 22 (see FIG. 6) is aligned is provided in the mask
410 as a transparent member. No particular limitations are imposed
on the shape of the reference mark 401, but the reference mark 401
is ring-shaped in the present embodiment.
[0107] The mirror 700 is detachably fitted in and fixed to the
spacer jig 430 so as to close the upper end opening portion of the
communicating hole 432 of the base jig 420 and to parallel the
protrusion 411 of the mask 410. That is, the mirror 700 is fixed to
the spacer jig 430, for example, by the action of a negative
pressure when the alignment apparatus is in the optical axis
adjustment mode. When the alignment apparatus is in the alignment
mode, the mirror 700 is detached from the spacer jig 430 to ensure
an optical path leading from the mask 410 to the nozzle plate 20
(see FIG. 6).
[0108] Here, let the distance from the reference mark 401 of the
mask 410 to the alignment mark 22 of the ink-jet recording head 220
(see FIG. 6) be "d". In this case, the mirror 700 is disposed such
that the distance from the reference mark 401 to the mirror 700 is
(1/2)d.
[0109] Setting the position of the mirror 700 to fulfill the
condition (1/2)d is not indispensable. By fulfilling the condition
(1/2)d, however, the position of the virtual image of the reference
mark 401 reflected in the mirror 700 can be brought into agreement
with the position of the alignment mark 22 of the nozzle plate 20.
Thus, the focal position of the bifocal microscopes 500, 600 is
brought to the virtual image during optical axis adjustment. By
this measure, the characteristic action and effect that the
alignment mark 22 is automatically focused on during alignment can
be obtained.
[0110] Optical Axis Adjustment:
[0111] The method of adjusting the optical axes L1 and L2 of the
bifocal microscopes 500 and 600 in the alignment apparatus
according to the present embodiment will be described.
[0112] 1) The mirror 700, which reflects the image of the reference
mark 401 to form its virtual image, is disposed between the mask
410 provided with the reference mark 401 and the ink-jet recording
head 220 (workpiece) such that the mirror 700 is parallel to and
opposed to the mask 410. An adjustment is made such that the
optical axis L1 is positioned at the center of the reference mark
401 to be coaxial, as shown in FIG. 8B.
[0113] 2) In the state of 1), the optical axis L1 is pointed in the
direction of the mirror 700 from the side of the mask 410, and the
reference mark 401 and a virtual image of the reference mark 401
reflected in the mirror 700 are simultaneously observed. Here, one
of the optical system, 501 (see FIG. 6), of the bifocal microscope
500 is used to focus on the real image of the reference mark 401,
and the other optical system 502 (see FIG. 6) is used to focus on
the virtual image of the reference mark 401 reflected in the mirror
700. Also, both images are superposed and observed. If, on this
occasion, the optical axis L1 is not orthogonal to the plane of the
mirror 700, but is inclined, the real image of the reference mark
401 and its virtual image 701 are displaced with respect to each
other, as shown in FIG. 8C.
[0114] Thus, the inclination of the optical axis L1 is adjusted to
superpose the virtual image 701 on the real image of the reference
mark 401. When the virtual image 701 is superimposed completely on
the real image of the reference mark 401, predetermined adjustment
of the optical axis L1 is completed.
[0115] 3) In connection with the optical axis L2 of the bifocal
microscope 600 as well, the same adjustment is made in the same
manner as in 2). As a result, the relative parallel relationship
between the optical axes L1 and L2 is fulfilled at the same time.
Pivoting of the optical axes L1, L2 attendant on such optical axis
adjustment is carried out by using an optical axis adjusting means
(not shown).
[0116] Alignment Method:
[0117] Next, an explanation will be offered for the method of
aligning the ink-jet recording head 220 with a predetermined
position by use of the alignment apparatus according to the present
embodiment.
[0118] FIGS. 9A to 9C are bottom views showing the status of the
alignment jig 400, when viewed from the bottom surface side, during
alignment of the ink-jet recording head 220.
[0119] 1) As shown in FIG. 9A, the reference marks 401, 401 are
confirmed by the bifocal microscopes 500, 600 from the bottom
surface side of the alignment jig 400.
[0120] 2) As shown in FIG. 9B, the fixing plate 250 is held by the
alignment jig 400. This is done by placing and fixing the fixing
plate 250 on the upper surface of the spacer jig 430. On this
occasion, the spacer jig 430 fixes the fixing plate 250 by sucking
the fixing plate 250 via the suction chambers 431.
[0121] 3) In the optical systems 501, 601 of the bifocal
microscopes 500, 600, images of the reference marks 401, 401 are
focused by the adjustment of the focal lenses 510, 610, and taken
into the CCDs 520, 620. In the other optical systems 502, 602,
images of the alignment marks 22, 22 are focused by the adjustment
of the focal lenses 511, 611, and taken into the CCDs 520, 620. As
a result, clear images focused on the reference marks 401, 401 and
the alignment marks 22, 22 are incorporated into the CCDs 520, 620.
That is, the optical systems (501, 502) and (601, 602) have the
optical axes L1, L2 in common, but can focus individually on the
objects at different positions (i.e., reference marks 401, 401 and
alignment marks 22, 22). Thus, they obtain clear images of the
reference marks 401, 401 and the alignment marks 22, 22 at
sufficient magnification with decreased depths of field.
[0122] 4) As shown in FIG. 9C, the ink-jet recording head 220 and
the fixing plate 250 are brought into contact via the adhesive
agent. That is, based on the images of the reference marks 401, 401
and the alignment marks 22, 22 obtained in the step 3) above, the
position of the ink-jet recording head 220 is adjusted such that
the reference marks 401, 401 and the alignment marks 22, 22 are in
the predetermined positional relationship, and also the ink-jet
recording head 220 is brought into contact with the fixing plate
250 via the adhesive agent.
[0123] The fixing plate 250 is positioned and held by the alignment
jig 400. Thus, the mask 410 and the ink-jet recording head 220 are
positioned with respect to each other, whereby the fixing plate 250
and the ink-jet recording head 220 can also be positioned with
respect to each other.
[0124] Positioning of the ink-jet recording head 220 with respect
to the fixing plate 250 may be performed by fine positional
adjustment using a micrometer or the like (not shown) while an
operator is visually recognizing the images on the CCDs 520, 620.
Alternatively, the positioning may be performed automatically by
subjecting the output images of the CCDs 520, 620 to image
processing to drive the micrometer or the like by a drive motor or
the like.
[0125] 5) The same step as the step in 4) above (FIG. 9C) is
repeated to position the plurality of ink-jet recording heads 220
on the fixing plate 250 sequentially. That is, with the optical
axes L1, L2 being fixed, the moving table 550 is moved in a
horizontal plane in the X-axis direction in FIG. 9C, whereby the
alignment marks 22, 22 of the other ink-jet recording heads 220
adjacent to each other are aligned with the reference marks 401,
401.
[0126] 6) The plurality of ink-jet recording heads 220 are pressed
against the fixing plate 250 at a predetermined pressure by means
of the pressing means 450, with the adhesive agent being cured,
whereby the ink-jet recording heads 220 are joined to the fixing
plate 250.
[0127] By so joining the fixing plate 250 and the plurality of
ink-jet recording heads 220, while performing positioning, the
fixing plate 250 and the nozzle rows 21A can be positioned with
respect to each other with high accuracy. Moreover, the relative
positioning of the nozzle rows 21A of the adjacent ink-jet
recording heads 220 can be carried out highly accurately.
Furthermore, the ink-jet recording head 220 is contacted with and
joined to the fixing plate 250 comprising the flat plate. Thus,
simply by joining the ink-jet recording head 220 to the fixing
plate 250, the relative positioning in the ink droplet ejection
direction of the plurality of ink-jet recording heads 220 is
performed. Hence, there is no need to align the plurality of
ink-jet recording heads 220 in the ink droplet ejection direction,
and deviation in the landing position of ink droplets can be
prevented reliably.
[0128] In the present embodiment, in particular, the space due to
the spacer jig 430 exists between the mask 410 provided with the
reference marks 401, 401 and the nozzle plate 20 provided with the
alignment marks 22, 22. Thus, the height positions of the reference
marks 401, 401 and the alignment marks 22, 22 are different from
each other. However, the focuses of the reference marks 401, 401
and the alignment marks 22, 22 can be adjusted, respectively, by
the two optical systems (501, 502) and (601, 602). Consequently,
the images of the reference marks 401, 401 and the alignment marks
22, 22 are so clear that high accuracy positioning can take
place.
Other embodiments
[0129] The alignment apparatus according to the above-described
embodiment has the two bifocal microscopes 500 and 600, but this is
not limitative. If positioning is performed for one alignment mark
22 by single alignment, at least one bifocal microscope 500 as an
optical means may be provided. Nor is the bifocal microscope 500
necessarily needed, and an ordinary single-focus microscope may be
used. However, it is only natural that the use of the bifocal
microscope 500 presents the aforementioned various advantages.
[0130] Needless to say, moreover, the workpiece is not limited to
the ink-jet recording head 220. Besides, the pressing means 450 is
provided on the alignment jig 400, but this is not limitative. For
example, if an ultraviolet curing adhesive agent is used as an
adhesive agent for joining the fixing plate 250 and the ink-jet
recording head 220, the adhesive agent is coated onto the joining
surface of the fixing plate 250. Then, with the fixing plate 250
and the ink-jet recording head 220 in contact, ultraviolet
radiation is applied to cure the adhesive agent, whereby the fixing
plate 250 and the ink-jet recording head 220 can be joined. Thus,
the pressing means 450 can be omitted. The ultraviolet curing
adhesive agent need not be cured, with the fixing plate 250 and the
ink-jet recording head 220 being pressed under a predetermined
pressure, unlike a thermosetting adhesive agent. If pressure is
applied, the ink-jet recording head 220 and the fixing plate 250
can be joined together with high accuracy, with positional
displacement between them being prevented.
[0131] Joining using the ultraviolet curing adhesive agent imparts
a relatively low joining strength. Thus, it is recommendable that
after the fixing plate 250 and the ink-jet recording head 220 are
joined using the ultraviolet curing adhesive agent, the periphery
of corners defined by the ink-jet recording head 220 and the fixing
plate 250 is fixed using a thermosetting adhesive agent. By this
measure, the fixing plate 250 and the ink-jet recording head 220
can be joined highly accurately and firmly to enhance
reliability.
[0132] In the above embodiments, the fixing plate 250 comprising
the flat plate is illustrated as the fixing member for joining the
plurality of ink-jet recording heads 220 thereto. However, the
fixing member is not limited to the fixing plate 250. For example,
the plurality of ink-jet recording heads 220 may be directly
positioned on and joined to the cover head 240. Even in this case,
the plurality of ink-jet recording heads 220 can be joined, with
high accuracy positioning, with the use of the aforementioned
alignment jig 400.
[0133] In the above embodiments, the ink-jet recording head 220 of
the flexural vibration type is illustrated, but this is not
limitative. It goes without saying that the invention can be
applied to head units having ink-jet recording heads of various
structures, such as, for example, an ink-jet recording head of the
longitudinal vibration type in which piezoelectric materials and
electrode-forming materials are alternately stacked, and expanded
and contracted in the axial direction, and an ink-jet recording
head for ejecting ink droplets by bubbles produced by heat
generation of a heat-generating element or the like.
[0134] In the above embodiments, the head unit having the ink-jet
recording heads for ejection of ink as liquid-jet heads to be
aligned is illustrated as an example. However, this is not
limitative, and the invention can be generally applied in producing
liquid-jet head units having wide varieties of liquid-jet heads.
Examples of the liquid-jet heads are recording heads for use in
image recording devices such as printers, color material jet heads
for use in the production of color filters such as liquid crystal
displays, electrode material jet heads for use in the formation of
electrodes for organic EL displays and FED (face emitting
displays), and bio-organic material jet heads for use in the
production of biochips. It should be understood that such changes,
substitutions and alterations can be made in the invention without
departing from the spirit and scope of the invention as defined by
the appended claims.
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